FIGS. 1-2 depict a portion of conventional head including a conventional perpendicular magnetic recording (PMR) head 10. FIG. 1 depicts the conventional PMR head 10 as viewed from the air-bearing surface (ABS), while FIG. 2 depicts the conventional PMR head 10 as viewed from the side. For clarity, the conventional PMR head 10 is not drawn to scale. The conventional PMR head 10 includes a conventional first pole 12, pole/flux guide 13, alumina insulating layer 14, alumina base layer 16 that may be considered part of the alumina insulating layer 14, a magnetic underlayer layer 17, a conventional PMR pole 18, insulating layer 20, shield gap 26, top shield 28, and insulating layer 30. Note that in certain other embodiments, the top shield 28 may also act as pole during writing using the conventional PMR head 10. The magnetic underlayer 17 is used as a seed layer for the magnetic material(s) in the conventional PMR pole 18. The conventional PMR pole 18 and the top shield 28 are surrounded by insulating layers 20 and 30. The conventional PMR pole 18 has sidewalls 22 and 24. The conventional PMR pole 18 also has a negative angle such that the top of the conventional PMR pole 18 is wider than the bottom of the conventional PMR pole 18. Stated differently, the angle θ of the sidewalls is less than ninety degrees in the conventional PMR pole 18.
FIG. 3 is a flow chart depicting a conventional method 50 for fabricating the conventional PMR head 10 using a damascene process. For simplicity, some steps are omitted. The conventional method 50 is described in the context of the conventional PMR head 10. The conventional method 50 starts after formation of the first pole 12 and the alumina layer 14. The alumina base layer 16 is formed, via step 52. Thus, the insulating layers 14 and 16 may be part of a single, larger insulating layer. The magnetic underlayer 17 that is used as a seed layer is deposited, via step 54. A photoresist mask is formed, via step 56. The mask is typically a photoresist mask having a trench that is substantially the same shape as the conventional PMR pole 18. The trench is refilled using the material for the conventional PMR pole 18, via step 58. The mask formed in step 56 is removed, via step 60. The PMR pole 18 is trimmed, via step 62. Typically, step 62 is performed using an ion beam etch that is carried out at an angle. In addition to thinning the PMR pole 18, the trim performed in step 62 removes any remaining magnetic underlayer 17 outside of the PMR pole 18. Fabrication of the PMR head 1 is then completed, via step 64. Step 64 may include formation of the insulating layer 20, lapping of the conventional PMR pole 18 to define the pole thickness, formation of the shield gap 25, and other processes.
Although the conventional method 50 may be used to fabricate the conventional PMR pole 18, there are drawbacks. For example, FIG. 4 depicts the conventional PMR head 10 during the trimming performed in step 60. At the end of the trimming in step 60, only the portion 17 of the magnetic underlayer 17′ should remain. Thus, the conventional PMR head 10 is typically over etched. At least some of the alumna base layer 16 is, therefore, etched during the pole trim in step 60. As can be seen in FIG. 4, atoms 25 removed from the alumina base layer 16, magnetic underlayer 17, and/or the PMR pole 18 may redeposit on the PMR pole 18. Some of these atoms 25 are redeposited on the sidewalls 22 and 24 of the conventional PMR pole 18. This redeposition is typically not a controlled process. Because of the redeposition on the PMR pole 18, the etch rate of the PMR pole 18 varies with time and location. As redeposition continues, the etch rate of the PMR pole 18 dynamically changes. Consequently, the width of the conventional PMR pole 18 may vary in an unpredictable manner. As a result, there may be variations in the track width of the conventional PMR head 10. In addition, the angle, θ, of the sidewalls 22 and 24 may vary. Such variations between conventional PMR poles 18 are undesirable. Furthermore, the surface roughness or profile of the sidewalls 22 and 24 may also vary due to redeposition. Consequently, geometry of the conventional PMR pole 18 may be compromised. As a result, the performance of the conventional PMR head 10 may be degraded.
Accordingly, what is needed is an improved method for fabricating a PMR head.